The core particle of a nucleosome is composed of how many histone proteins?

The following is a sample segment of a $DNA$ strand. What does the sequence of bases on the opposite strand show? Is there anything special about it?
$5' -GAATTC -3'$
$3' -CTTAAG -5'$

Jumping genes in maize were discovered by

The backbone of the $DNA$ molecule is composed of which of the following?

$NHC$ protein stands for.......

The length of $DNA$ double helix in human sperm is approximately . . . . . . .